Energy management systems that utilize BAS (building automation systems), BEMS (building and energy management systems), and so forth have heretofore been proposed in order to optimize use efficiency of energy such as electric power and heat in buildings such as office buildings and factories.
These energy management systems also include a supply-demand control technique which matches power generation and power consumption. This matching is made by using, in combination with power from a bulk power system, renewable energy supplied from power generation such as wind and photovoltaic power generation, energy supplied from an energy storage device or the like.